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Tracking Zone Entries And Zone Exits

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I tracked zone exits for one period out of sheer curiosity after watching what I thought was an inordinate number of touches by Jeff Petry prior to the puck leaving the zone.  I was right.  Petry handled zone exits ~80% of the time when he was on the ice with Theo Peckham:

Peckham touched the puck 9 times in the defensive zone and moved it forward just once on his own, noted in bold above. He got the puck out of the zone on his first touch, but it was a desperation clear and the puck went back to the Bruins. Of his other 7 touches, 6 of them were almost immediate passes to Jeff Petry, typically before Peckham could take a full stride. Remember the numbers from Jonathan's study - Peckham played 7 minutes at even strength and didn't move the puck out of the zone at all. In the game against the Bruins, he moved it once in the first period. Now there's a man who knows his limitations.

Jonathan Willis tracked all zone exits for an entire game in an effort to determine who was driving possession:

For last night’s season opener against the Penguins, I decided to see which Oilers’ players spent the greatest amount of time moving the puck either a) out of the defensive zone or b) into the offensive zone at even-strength.

But it's on the other side of the neutral zone where Eric from Broad Street Hockey has focused his tracking efforts, which he outlines in his article, Zone entries: Individual contributions to team success.

Eric's reason for tracking entries is simple:

In the past, our zone entry data has been limited to a focus on puck possession: which individuals moved the puck into the offensive zone and what outcomes followed their individual play. By bringing in the data about who else is on the ice, we can look at people who help bring the puck forward with off-puck decisions and before-the-blue-line passes. We can look at who helps generate shots after the puck enters the zone.

And most importantly we can look at defensive contributions for the first time: which players help prevent their opponents from carrying the puck in and limit their opponent's shots per entry?

The end result of his work is a series of new metrics he's developed to directly measure puck movement and effectiveness:

  • Neutral zone winning percentage: what fraction of the occasions that the puck is in the neutral zone does it get pushed forwards into the offensive zone? (Team total: 51.2%)
  • Decisive neutral zone wins: what fraction of the neutral zone wins result in entering the offensive zone with control of the puck? (Team total: 56.5%)
  • Decisive neutral zone losses: what fraction of the neutral zone losses result in the opponents entering the team's defensive zone with control of the puck? (Team total: 51.2%)
  • Shot generation: how often does the team generate shots when they enter the offensive zone with possession of the puck? (Team total: 0.51 shots/entry)
  • Shot prevention: how often does the opponent generate shots when they enter the team's defensive zone with possession of the puck? (Team total: 0.51 shots/entry)

So now we've got a framework to track the puck as it moves out of the defensive zone and into the offensive zone.  Eric's scripts allow us to capture players and time on ice and his and Jonthan's metrics allow us to derive the numbers to compare players and teams.  Tracking these numbers is the edge of the universe of advanced stats.  All we need now are a few volunteers to explore it.  If you're interested in tracking a game or two, or even just an individual player, let us know.